The invention relates to apparatus for making can bodies.
In conventional apparatus for making can bodies, can bodies stripped from the punch are picked up on an endless chain conveyor which carries spaced sets of flexible fingers. The conveyor is driven at a constant speed in timed relation to the punch and delivers the can bodies to a gravity conveyor for delivery to a trimmer for trimming the top edge of the can body.
The invention provides an improvement in such apparatus in which can bodies stripped from the punch, after the punch has passed through a die and engaged a tool for forming a dome in the bottom wall of the can body, are picked up, supported and conveyed away from the punch on a rotary turret which is driven in continuous rotation at a cyclically varying angular velocity.
According to the present invention, there is provided apparatus for making can bodies comprising: a punch mounted for reciprocation on the apparatus; a rotary turret mounted on the apparatus for rotation about a horizontal axis parallel to the axis of the punch; a plurality of conveying elements spaced circumferentially around the turret and extending generally radially from the turret and adapted to pick up, support and convey can bodies stripped from the punch as the turret rotates; and drive means mounted on the apparatus for driving the turret in continuous rotation at a cyclically varying angular velocity such that the angular velocity of a flexible element is less at the moment when it engages a can body stripped from the punch than at other times.
The provision of a rotary turret provides several advantages over a conventional chain conveyor. Firstly, a rotary turret is smaller, simpler and has less components. It also enables more precision to be applied in the control of its drive. The conveyor must operate in a wet area of the apparatus where a cooling and lubricating liquid is present and the maintenance of chain conveyors in such an environment has obvious disadvantages. The drive chains to a turret conveyor can be located in dry areas of the apparatus.
The provision of a cyclically varying drive to the turret enables the speed of the conveying elements on the turret to be controlled so that they are moving more slowly at the moment when they first engage the can bodies than at other times. The varying speed of the elements also allows the xe2x80x9cwindowxe2x80x9d of time during which the punch must pass into and out of the space between adjacent elements, to be increased. The relatively slow movement of the conveying elements at the moment of impact with the can bodies enables the overall speed of the apparatus to be increased. With apparatus in accordance with the invention a variation of xc2x125% has been achieved in the speed of the conveying elements. This has enabled the overall apparatus speed to be increased from 400 can bodies/minute to 500 can bodies/minute without causing damage to the can bodies from impact with the conveying elements.
An embodiment of the invention is described below with reference to the accompanying drawings in which: